Blood clotting test is performed for various purposes such as for identifying clinical conditions of coagulation fibrinolytic system, for diagnosing DIC (disseminated intravascular coagulation), for checking effects of thrombus treatments, or for diagnosing hemophilia. Conventionally, blood clotting test has been performed by visually identifying fibrin precipitation which is a final point of blood clotting reaction. However, after 1960's, blood clotting analysis devices which are developed for improving test throughputs and precisions have been used in usual tests.
In detecting fibrin precipitations by blood clotting analysis devices, methods such as electric resistance detection, optical detection, or mechanical methods are used, in particular, optical detection is a contactless method in which samples do not touch with foreign objects in clotting reactions. Thus optical detection is widely used. There are two types of optical detections; a transmitted light detection in which, variation of transmitted light, is measured when aggregated substances are generated in reaction containers; and a scattered light detection in which scattered light is detected. Both methods analyze the detected chronological light intensity to calculate clotting time. Various methods have been proposed so far.
In the technique described in Patent Literature 1 listed below: times T1 and T2, at which the most recently acquired signals become X-times and Y-times (0<X<Y<1) larger respectively, are searched by scanning from the most recently acquired signals toward the initially acquired signals; polynomial regression, analysis is performed with respect to the signals from the time T1 to the time T2; and the clotting time is calculated from the acquired approximated curve. Accordingly, the unevenness of data is removed, thereby attempting to accurately calculate the clotting time.